A wide variety of memory devices are in common use. One type of memory device that is becoming increasingly popular are memory devices that have a plurality of input/output (“I/O”) ports. Prior art multi-port memory devices normally have a fixed memory capacity that is accessible through each port. For example, a 1 Gb memory device having 4 ports would normally have 256 Mb of storage accessible through each port. The fixed capacity per port approach is satisfactory for many applications. However, many applications require a memory device in which different memory access devices coupled to the memory device through respective ports having different data storage requirements. In such case, the tradeoff is either to have insufficient capacity available to some memory access devices or to have excessive capacity available to other memory access devices. Either approach results in some performance or cost disadvantages.
One solution to the above limitations of the fixed capacity per port approach may be to provide different fixed capacities for each of several ports. For example, in the above-described 1 Gb memory device having 4 ports, a processor may require 512 Mb of capacity and would thus access the memory device through a port with 512 Mb available, a baseband processor may require 256 Mb of capacity and would thus access the memory device through a port with 256 Mb available, and two other memory access devices may each require 128 Mb of capacity and would thus access the memory device through respective ports with 128 Mb accessible through each port. While this approach might be ideal for some applications, it may not be acceptable for other applications. For example, another user of the memory device might need a memory device with 256 Mb accessible through each of the 4 ports or a memory device with 512 Mb accessible through one port, 256 Mb accessible through 2 ports, and no capacity accessible through the 4th port. While this approach could be alleviated to some extent by manufacturing memory devices having a wide variety of port configurations, this approach would require memory device manufacturers to design, manufacture, stock and sell a large number of different memory devices. The cost of this approach would undoubtedly result in such memory devices being relatively expensive.
There is therefore not an entirely acceptable solution for the need for multi-port memory devices having a wide variety of port configurations.